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MODULE 15 - Cardiorespiratory and Haematopoietic Disease > PATHOLOGY - Canine Acquired Cardiac Disease > Flashcards

PATHOLOGY - Canine Acquired Cardiac Disease Flashcards

1
Q

What is myxomatous mitral valve disease?

A

Myxomatous mitral valve disease is a degenerative valvluar disease characterised by changes in the cellular and intracellular constituents of the valve, resulting in valve leaflet and chordae tendinae thickening

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2
Q

Which signalment is more prone to myxomatous mitral valve disease?

A

Medium sized, older male dogs

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3
Q

Which dog breed is predisposed to myxomatous mitral valve disease?

A

Cavalier King Charles Spaniels

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4
Q

Describe the pathophysiology of myxomatous mitral valve disease

A

The degeneration of the mitral valve results in valvular insufficiency, preventing complete apposition of the valve leaflets during systole resulting in blood regurgitation from the left ventricle back into the left atrium. This regurgitation eventually results in volume overload and left ventricular compensatory eccentric hypertrophy and left atrial enlargment. The hearts ability to pump blood effectively will progressively worsen along with the volume overload, this eccentric hypertrophy will also cause dilation of the valvular annular ring, resulting in a worsening regurgitation into the left atrium and a worsening volume overload which will eventually cause a backup of blood into the pulmonary veins, causing increased hydrostatic pressure resulting in pulmonary oedema and left-sided congestive heart failure. This can also progress to right-sided congestive heart failure as pulmonary hypertension will increase the afterload on the right side of the heart, resulting in pressure overload, concentric hyoertrophy of the right ventricle and eventual right-sided congestive heart failure

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5
Q

What are the five clinical signs of myxomatous mitral valve disease?

A

Asymptomatic
Left sided apical systolic plateau murmur
Syncope
Exercise intolerance
Signs of left-sided congestive heart failure

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6
Q

What can be the three underlying causes of the cough seen with myoxmatous mitral valve disease?

A

Cardiogenic pulmonary oedema
Airway obstruction secondary to cardiomegaly
The signalement for myoxmatous mitral valve disease are also predisposed to respiratory disease

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7
Q

How can you determine the severity of myxomatous mitral valve disease on clinical exam?

A

The severity of the myxomatous mitral valve disease corresponds with with intensity of the heart murmur

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8
Q

What is indicated by a grade I or II heart murmur associated with myoxmatous mitral valve disease?

A

A grade I or II heart mumur indicates there is a mitral valve insufficiency but no cardiac remodelling (stage B1)

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9
Q

What is stage A of myxomatous mitral valve disease?

A

Dogs that are at risk of developing myxomatous mitral valve disease due to their signalement but have no structural or clinical signs

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10
Q

What is stage B1 of myxomatous mitral valve disease?

A

Dogs that have clear valvular insufficiency but there is no cardiac remodelling

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11
Q

What is stage B2 of myxomatous mitral valve disease?

A

Dogs with clear valvular insufficiency and cardiac remodelling

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12
Q

What is stage C of myxomatous mitral valve disease?

A

Dogs with clinical signs of congestive heart failure

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13
Q

What is stage D of myxomatous mitral valve disease?

A

Dogs with end-stage congestive heart failure and are refractory to treatment

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14
Q

What are the characteristic signs of myxomatous mitral valve disease on a radiograph?

A

Cardiomegaly (particulalry of the left atrium)
Dorsal displacement of the trachea due to left atrial enlargement
Displacement of the bronchi on VD by left atrial enlargement (cowboy sign)
Signs of left-sided congestive heart failure (such as perihilar alveolar lungs signs and increased size of the pulmonary veins)

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15
Q

Which three arrhythmias can sometimes be seen with myoxmatous mitral valve disease?

A

Atrial fibrillation
Supraventricular premature contractions
Ventricular premature contractions

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16
Q

What can be indicated by sinus arrhythmia in dogs with a murmur associated with myxomatous mitral valve disease?

A

Sinus arrhythmia indicates that the myxomatous mitral valve disease is not yet severe, and there is a low chance that there has been cardiac remodelling

However this can be misleading if the dog also has a disease causing high vagal tone

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17
Q

What are the characteristic signs of myxomatous mitral valve disease on echocardiography?

A

Thickened and nodular mitral valve
Left atrial enlargement
Left ventricular eccentric hypertrophy
Turbulent blood flow at the mitral valve (doppler)

Right parasternal long axis view of the left ventricle and atrium
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18
Q

Which two biomarkers can be indicative of myxomatous mitral valve disease?

A

NTproBNP
Cardiac troponin I

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19
Q

What can be indicated by increased plasma levels of NTproBNP?

A

NTproBNP plasma levels increase when cardiac size increases

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20
Q

Why is NTproBNP an unreliable biomarker of cardiac disease?

A

NTproBNP is non-specific to cardiac disease and has significant biological variability

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21
Q

What can be indicated by increased plasma levels of cardiac troponin 1?

A

Cardiac troponin 1 plasma levels increase when the is cardiac damage

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22
Q

In dogs at risk of myxomatous mitral valve disease, what should owners monitor for at home?

A

An increased resting respiratory rate as this can precede signs of left-sided congestive heart failure

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23
Q

How should you treat stage A myxomatous mitral valve disease?

A

No treatment

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24
Q

How should you treat stage B1 myxomatous mitral valve disease?

A

No treatment

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25
Q

How should you treat stage B2 myxomatous mitral valve disease?

A

Treat with pimobendan

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26
Q

How should you treat stage C myxomatous mitral valve disease?

A

Treat with pimobendan and diuretics

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27
Q

What is the prognosis for dogs with myxomatous mitral valve disease exhibiting clinical signs of left-sided congestive heart failure?

A

Generally a prognosis of 9 months

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28
Q

What is dilated cardiomyopathy?

A

Dilated cardiomyopathy is an inherited generalised disease/dysfunction of the myocardium characterised by ventricular dilation

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29
Q

Which signalement is more prone to dilated cardiomyopathy?

A

Large, middle age to old male dogs

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30
Q

Which dog breeds are predisposed to dilated cardiomyopathy?

A

Doberman
Irish Wolfhound

Irish Wolfhound
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31
Q

Describe the pathophysiology of dilated cardiomyopathy?

A

Dilated cardiomyopathy is generalised dysfunction of the myocardium resulting in systolic dysfunction which causes a reduction in cardiac output which results in an increased end-diastolic volume, volume overload and compensatory ventricular eccentric hypertrophy. The hearts ability to pump blood effectively will progressively worsen along with the volume overload, resulting in a backup of blood into the pulmonary veins (on the left side of the heart) and systemic circulation (on the right side of the heart), increasing hydrostatic pressure resulting in pulmonary and systemic oedema and congestive heart failure

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32
Q

What are the seven clinical signs of dilated cardiomyopathy?

A

Asymptomatic
Low grade or no mumur
Arryhthmias
Syncope
Exercise intolerance
Signs right and left sided congestive heart failure
Weak pulses

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33
Q

Why is there often not a heart murmur associated with dilated cardiomyopathy?

A

There is not always a heart murmur as the primary issue in dilated cardiomyopathy is related to the myocardial structure and function rather than turbulent blood flow that typically results in a heart murmur

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34
Q

How does dilated cardiomyopathy cause arrhythmias?

A

Arrhythmias can occur due to structural damage to the heart due to dilated cardiomyopathy

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35
Q

Why is it recommended to begin screening for arrhythmias in breeds predisposed to dilated cardiomyopathy?

A

Arrhythmias can potentially cause sudden death so it it recommended to begin screening for arrhythmias from 3 years old in dog breeds predisposed to dilated cardiomyopathy, using a 24 holter ECG

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36
Q

(T/F) Male dogs with dilated cardiomyopathy develop structural changes before they develop arrhythmias

A

TRUE.

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37
Q

(T/F) Female dogs with dilated cardiomyopathy develop structural changes before they develop arrhythmias

A

FALSE. Female dogs with dilated cardiomyopathy develop arrhythmias before they develop structural changes

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38
Q

What is stage A of dilated cardiomyopathy?

A

Dogs that are at risk of developing dilated cardiomyopathy due to their signalement but have no structural or clinical signs

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39
Q

What is stage B1 of dilated cardiomyopathy?

A

Dogs that have arrhythmias but there is no cardiac remodelling

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40
Q

What is stage B2 of dilated cardiomyopathy?

A

Dogs that have cardiac remodelling ± arryhthmias

41
Q

What is stage C of dilated cardiomyopathy?

A

Dogs with clinical signs of congestive heart failure

42
Q

What is stage D of dilated cardiomyopathy?

A

Dogs with end-stage congestive heart failure that is refractory to treatment

43
Q

What are the characteristic signs of dilated cardiomyopathy on echocardiography?

A

Eccentric ventricular hypertrophy
Poor systolic function

Right parasternal long axis view of the left ventricle and atrium
44
Q

Which two biomarkers can be indicative of dilated cardiomyopathy?

A

NTproBNP
Cardiac troponin I

45
Q

Which additional test can you do to help diagnose dilated cardiomyopathy?

A

24 hour arrhythmia monitoring using a holter ECG

46
Q

How do you treat dilated cardiomyopathy?

A

Treat with pimobendan

47
Q

What is the prognosis for dogs with dilated cardiomyopathy exhibiting clinical signs of congestive heart failure?

A

Prognosis of approximately a year, typically only 3-4 months in Dobermans

48
Q

What is secondary dilated cardiomyopathy?

A

Secondary dilated cardiomyopathy is cardiomyopathy with an underlying pathological cause

49
Q

Give an example of an underlying aetiology of secondary dilated cardiomyopathy

A

Nutritional difficiencies - such as taurine and L-cartinine deficiency

50
Q

What is the most common acquired cardiac disease seen in Boxers?

A

Arrhythmogenic (right ventricular) cardiomyopathy (ARVC)

A form of primary dilated cardiomyopathy

51
Q

Which other dog breed is predisposed to arrhythmogenic (right ventricular) cardiomyopathy (ARVC)?

A

English Bulldogs

52
Q

Which diagnostic test is most useful for screening dogs with suspected arrhythmogenic (right ventricular) cardiomyopathy?

A

24 hour arrhythmia monitoring using a holter ECG

53
Q

What is pericardial effusion?

A

Pericardial effusion is an abnormal accumulation of fluid within the pericardial cavity

54
Q

What is the most common type of effusion in the pericardium?

A

Haemorrhagic effusion

55
Q

Why is it important to do a PCV on the effusion collected from a pericardiocentesis?

A

You should do a PCV on the effusion as the PCV has to be above 10% to be classified as a haemorrhagic effusion

56
Q

What is cardiac tamponade?

A

Cardiac tamponade is compression of the heart due to a pericardial effusion

57
Q

Describe the pathophysiology of cardiac tamponade

A

Cardiac tamponade is compression of the heart due to pleural effusion which restricts the filling of the cardiac chambers during diastole, resulting in decreased cardiac output. Cardiac tamponade has a more significant effect on the right side of the heart as the right side operates at lower pressures compared to the left side, which means the pericardial effusion will exert more pressure on the right-sided heart chambers, resulting in impaired filling, reduced output and eventually causing a backup of blood and right-sided congestive heart failure. Due to the reduced cardiac output from the right side of the heart into the pulmonary artery, there will be reduced venous return to the left side of the heart resulting in a decreased cardiac output

58
Q

What is the difference between acute and chronic pericardial effusion?

A

Acute pericardial effusion is the life-threatening rapid accumulation of fluid in the pericardium and compression of the heart, whereas chronic pericardial effusion is the slow build up of fluid over time, allowing the pericardium to stretch out and accumulate more and more fluid until there is eventual compression of the heart

59
Q

What are the seven clinical signs of acute pericardial effusion and cardiac tamponade?

A

Severe weakness/collapse
Syncope
Sudden death
Dyspnoea
Muffled heart sounds
Tachycardia
Pulsus paradoxus

60
Q

What are the eight clinical signs of chronic pericardial effusion?

A

Exercise intolerance
Increased thirst
Vomiting
Abdominal distension
Muffled heart sounds
Tachycardia
Pulsus paradoxus
Signs of right sided congestive heart failure

61
Q

Why do you get muffled heart sounds with pericardial effusion?

A

The increased layer of fluid within the pericardium will cause the heart sounds to be muffled on auscultation

62
Q

What can be detected on an ECG that is indicative of pericardial effusion?

A

Electrical alternans of the QRS complexes

Note the alternating height of the QRS complexes
63
Q

How does pericardial effusion cause electrical alternans of the QRS complexes on ECG?

A

The fluid accumulation in the pericardial cavity creates a ‘swinging’ motion of the heart when it beats, which changes the position of the heart relative to the electrodes which can lead to a variation in the electrical signals detected by the ECG

64
Q

How do you treat pericardial effusion and cardiac tamponade?

A

Pericardiocentesis

Dog positioned in left lateral recumbency for pericardiocentesis
65
Q

What are the two most common causes of pericardial effusion?

A

Idiopathic
Neoplasia

66
Q

Give an example of a congenital cause of pericardial effusion

A

Peritoneo-pericardial diaphragmatic hernia

67
Q

What are the most common neoplastic causes of pericardial effusion?

A

Cardiac haemangiosarcoma (most common and most aggressive)
Neuroendocrine tumours
Pericardial mesothelioma

68
Q

Which three breeds are predisposed to cardiac haemangiosarcomas?

A

German Shepherds
Golden Retrievers
Labrador Retrievers

69
Q

Where are cardiac haemangiosarcomas usually found?

A

Right atrium
Right auricle

70
Q

Where do haemangosarcomas often metastasise to or from?

A

Spleen

71
Q

What is a characteristic feature of haemangiosarcomas?

A

Haemangosarcomas have a high level of angiogenesis and these vessels often burst and cause haemorrhage - i.e. if the dog also has a splenic haemangiosarcoma, there can be a haemoabdomen

72
Q

What is the most common neuroendocrine tumour that causes pericardial effusion?

A

Chemodectoma

73
Q

(T/F) Chemodectomas are usually malignant

A

FALSE. Chemodectomas as usually benign however they can grow very large and compress the heart chambers

74
Q

Why are brachycephalic breeds prone to chemodectomas?

A

Chemodectomas originate from chemoreceptors in the aortic root and can be triggered by hypoxia. Brachycephalics are hypoxic for the majority of their lifespan and thus are at increased risk of chemodectomas

75
Q

(T/F) There is often no mass associated with pericardial mesotheliomas

A

TRUE. Often there is only pericardial effusion associated with pericardial mesotheliomas

76
Q

What is constrictive pericardial disease?

A

Constrictive pericardial disease is the stiffening and reduced compliance of the pericardium which restricts the filling of the cardiac chambers during diastole, resulting in decreased cardiac output and eventually congestive heart failure

77
Q

How do you treat constrictive pericardial disease?

A

Surgical removal of the pericardium

78
Q

What is pulmonary hypertension?

A

Pulmonary hypertension is a pathological increase in the mean arterial pressure (MAP) of the pulmonary arteries

79
Q

How does pulmonary hypertension cause right-sided heart failure?

A

Pulmonary hypertension increases the afterload on the right ventricle, causing pressure overload and compensatory concentric hypertrophy of the right ventricle which will eventually progress to right sided heart failure

80
Q

What are five possible causes of pulmonary hypertension?

A

Primary pulmonary arterial hypertension
Left sided heart disease
Secondary to respiratory disease
Pulmonary thromboembolisms
Parasitic (heart and lungworms)

81
Q

How do you diagnose dirofilaria immitis?

A

Positive antigen test for macrofilariae and a second confirmatory test such as detection of adult worms on echocardiography

82
Q

Why is it so important to get a confirmatory test for dirofilaria immitis?

A

It is important to get a confirmatory test for dirofilaria immitis as melarsomine -one of the drugs used to treat this parasite - is arsenic based and can be very toxic, so you want to be very sure that it is indicated

83
Q

How do you treat dirofilaria immitis?

A

Macrocyclic lactones to kill the microfilariae
Melarsomine to kill the adult worms
Surgical removal of the adult worms

84
Q

What are the main clinical signs of an angiostrongylus vasorum infection?

A

Exercise intolerance
Tachypnoea
Coughing
Signs of haemostatic disorder
Cardiovascular dysfunction

85
Q

How does a angiostrongylus vasorum infection increase coagulation time?

A

Angiostrongylus vasorum adults secrete products which interfere with coagulation and thus increase coagulation time

86
Q

What are the two methods that can be used to diagnose an angiostrongylus vasorum infection?

A

Identify L1 larvae in the faeces using Baermann apparatus
Antigen test

87
Q

What can predispose dogs to endocarditis?

A

Subaortic stenosis
Aortic valve regurgitation
Corticosteroids

88
Q

What are the four main consequences of infective endocarditis?

A

Persistent bacteraemia
Valvular insufficiency
Septic embolisation
Antigen-antibody complex deposition

89
Q

In which valves is endocarditis most commonly seen in dogs?

A

Mitral valve
Aortic valve

90
Q

Where on the mitral valve does endocarditis typically develop and why?

A

Endocarditis typically develops on the atrial side of the mitral valve as there is less pressure on that side which allows for better adherence of the bacterial vegetations

91
Q

Where on the aortic valve does endocarditis typically develop and why?

A

Endocarditis typically develops on the ventricular side of the aortic valve as there is less pressure on that side which allows for better adherence of the bacterial vegetations

92
Q

What are some of the potential clinical signs of endocarditis?

A

New heart murmur
Pyrexia
Hindlimb weakness

93
Q

How does endocarditis cause a heart murmur?

A

Bacteria causing infective endocarditis produce proteinase enzymes which can cause structural damage to the heart valves, resulting in the inability of the valves to close properly resulting in the backflow, regurgitation and turbulence of blood, causing a heart murmur

94
Q

What are the three major criteria required to diagnose endocarditis?

A

Echocardiogram positive for endocarditis
Valvular insufficiency
Positive culture result

95
Q

Which diagnostic tests can you do to determine the source of infection in an animal with endocarditis?

A

Blood culture
Urine culture
Diagnostic imaging

96
Q

How should endocarditis be treated?

A

Infectious endocarditis should be treated with high dose bactericidal antibiotics over a long duration (usually for six weeks or more)

97
Q

What is myocarditis?

A

Myocarditis is inflammation of the myocardium

98
Q

Which virus most commonly causes myocarditis in dogs?

A

Canine parvovirus 2

MODULE 15 - Cardiorespiratory and Haematopoietic Disease (21 decks)

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